MQD2H/3H DIAPHRAGM PUMP • OPERATION MANUAL — REV. # 8 (07/31/20) — PAGE 9
NEVER place the pump on soft soil. The suction hose or
pipe connection should always be checked for tightness
and leaks. A small suction leak in the hose or fittings could
prevent the pump from priming.
Elevation
Higher elevations will effect the performance of the pump.
Due to less atmospheric pressure at higher altitudes,
pumps do not have the priming ability that they have at
sea level. This is due to the “thinner air” or lack of oxygen
at higher altitudes.
A general rule of thumb is that for every 1,000 feet of
elevation above sea level a pump will lose one foot of
priming ability.
For example, in Flagstaff, Arizona where the elevation is
approximately 7,000 feet, the pump would have a suction
lift of only 18 feet rather than the 25 feet at sea level. Table 4
shows suction lift at various elevations.
Table 4. Suction Lift at Various Elevations
Altitude
Feet
(Meters)
Suction Lift in Feet (Meters)
Sea Level 10.0 (3.048) 15.0 (4.572) 20.0 (6.096) 25.0 (7.620)
2,000 (610) 8.80 (2.680) 13.2 (4.023) 17.6 (5.364) 22.0 (6.705)
4,000 (1,219) 7.80 (2.377) 11.7 (3.566) 15.6 (4.754) 19.5 (5.943)
6,000 (1,829) 6.90 (2.103) 10.4 (3.169) 13.8 (4.206) 17.3 (5.273)
8,000 (2,438) 6.20 (1.889) 9.30 (2.834) 12.4 (3.779) 15.5 (4.724)
10,000 (3,048) 5.70 (1.737) 8.60 (2.621) 11.4 (3.474) 14.3 (4.358)
Table 5 shows percentage drops in performance as
elevation increases.
Table 5. Performance Loss at Various Elevations
Altitude
Feet (Meters)
Discharge Flow Discharge Head
Sea Level 100% 100%
2,000 (610) 97% 95%
4,000 (1,219) 95% 91%
6,000 (1,829) 93% 87%
8,000 (2,438) 91% 83%
10,000 (3,048) 88% 78%
GENERAL INFORMATION
APPLICATION
The MQD2H and MQD3H diaphragm pumps are designed
to be used for dewatering applications. The suction and
discharge ports on the MQD2H use a 2-inch diameter
opening, which allows the pump to pump at a rate of
approximately 3,000 gallons/hour (gph) or 11,340 liters/
hour (lph). The suction and discharge ports on the MQD3H
use a 3-inch diameter opening, which allows the pump to
pump at a rate of approximately 5,400 gallons/hour (gph)
or 20,456 liters/hour (lph).
Diaphragm pumps use a positive displacement design
rather than centrifugal force to move water through the
casing. This means the pump will deliver a specific amount
of flow per stroke, revolution or cycle. These pumps are
commonly referred to as mud hogs, mud hens and mud
suckers. Their names reflect their popularity for use in
applications where shallow depths and slurry water render
centrifugal pumps ineffective.
Power Plant
These diaphragm pumps are powered by a 4.0 horsepower
air cooled, 4-stroke, single cylinder HONDA GX120 gasoline
engine that incorporates a low “Oil Alert Feature”. The drive
shaft of the engine is coupled to an offset connecting rod
that is coupled to a flexible diaphragm. The connecting rod
alternately raises (expands) and lowers (contracts) the
diaphragm at a rate of 60 cycles per minute at maximum
engine RPM (2,750).
Oil Alert Feature
In the event of low oil or no oil, the HONDA GX120 engine
has a built-in oil alarm engine shut-down feature. In the
event the oil level is low the engine will automatically shut
down.
Suction Lift
This pump is intended to be used for dewatering applications
and is capable of suction lifts up to 25 feet at sea level. For
optimal suction lift performance keep the suction hose or
line as short as possible. In general, always place the pump
as close to the water as possible.
Pump Support
The pump should always be placed on solid stationary
ground in a level position.